Building a PV-Erik, or PV-Frankenstein, depending on how you see it.

So, I last wrote that I was fixing a Conrad Johnson PV-10, which was true, but I also wrote that I would be returning to power conditioning, which is only partially true.

Instead of focusing on the power conditioner testing which I had planned, I instead started looking around at the CJ schematics for the PV-10 and 12, and with some helpful ideas from UncleStu at Audio Asulym I decided I would transform my PV-10 into a PV-10 on mega steroids. The challenge is to make it as good of a preamp of it's kind as I could, without actually harming the reasons I fell in love with it in the first place, and I think I have a way of doing this. By leaving the audio circuit 99% untouched, and focusing the work I do on the power supply.

If you scroll down you'll see the insides of a PV-10AL. Notice all that bare space to the right? That's where the phonograph section would normally go if you bought the PV-10A (sans 'L'). In this space I am going to stick two of these circuit boards which you see pictured. They are power supply boards, one for each tube. This will hopefully improve channel separation, power supply regulation, and bass response. They will be chock full of Solen and Cardas Golden Ratio capacitors.

By the way, this is the first PCB I've ever designed for myself. I've designed many, but always for a client or employer. This is the first time I've done one and paid for it out of my own pocket. Pretty nice huh? The design is based on the B+ power supply regulator stages used in the PV-5 through PV-12. It's a little different in that I'm using a TIP50 transistor, which gives me higher breakdown voltages and seriously higher power dissipation than the MJE340s which CJ is so fond of, and seem to blow out so regularly in the preamps this old. So, serious overkill here.

The first batch of parts arrive from DigiKey tomorrow, and then about a week later the fancy caps, jumper wire, etc. arrive from The Parts Connexion.

Stay tuned folks, this really is going to be a major overhaul of the power supply of this preamp, and I'll be documenting all the way.

I think you will see that the mods all stay true to the original circuit philosophy. The only mods I intend to the audio circuit itself are a pair of 0.22uF Cardas caps. Maybe. If I like it. Let's see what the power supply mods do to this baby giant killer first.